The emergency department (ED) is a part of a hospital for treating people who have just come to the hospital, need to be treated quickly even without an appointment. These people may have been hurt, or they may have suddenly become very ill.
Patients come to an emergency department with little warning. Many come in an ambulance. Emergency departments often have staff working all day and all night, on every day of the week. This is because patients can arrive at any time. To work in those places, doctors and nurses must be trained in emergency medicine.
There are many different names for an emergency department. They are often called an emergency room (ER), even if they are bigger than one room. They may also be called an emergency ward (EW) or emergency unit. In the United Kingdom and Ireland, they are usually called accident & emergency department (A&E) and less often as a casualty department.
A 2005 patient study found an average emergency room wait time from 2 hours in Iowa to more than 5 hours in Arizona. The Midwest had the highest number of emergency room visits (460 per 1,000 people). The West had the lowest number.